Answer
a) $8.8\%$
b) $8.75\%$
Work Step by Step
In the formula for compound interest with
let $P=\$10.500$
$t=12$
$A=\$30.000$
a) $m=4$
$A=P(1+\frac{r}{m})^{tm}$
$30000=10500(1+\frac{r}{4})^{12(4)}$
$(1+\frac{r}{4})^{48}=\frac{20}{7}$
$r\approx0.088\approx 8.8\%$
b) $A=Pe^{rt}$
$30000=10500e^{12r}$
$e^{12r}=\frac{20}{7}$
$r \approx 0.0875 = 8.75\%$
